Abstract

Background: This study aims to compare the patency rates of
radiocephalic arteriovenous fistulas prepared preserving the
perivenous vascular tissues versus those prepared using the
conventional technique.

Methods: A total of 169 patients (107 males, 62 females;
mean age 59.5 years; range, 39 to 87 years) who underwent a
radiocephalic arteriovenous fistula construction were included
in this study. In 95 patients, the tissues surrounding the cephalic
vein were stripped off as per the conventional method, while the
no-touch technique preserving the perivenous vascular tissues
was utilized for vein harvesting in 74 patients. Patients were
followed-up to compare primary and secondary patency rates of
the arteriovenous fistulas at one year.

Results: Fistula failure developed in 22 patients within the first
year resulting in primary patency rates of 90.5% versus 84.2%
for the no-touch and the conventional groups, respectively
(p=0.225). Likewise, secondary patency rates were 94.6% versus
93.7% for the no-touch and the conventional groups, respectively
(p=0.803). The two groups did not differ with regards to primary
or secondary patency rates.

Conclusion: Findings of this study were not in favor of the
no-touch technique compared to the conventional methods in
terms of arteriovenous fistula patency at one year.

Distal arteriovenous (AV) fistulas represent the
preferred vascular access route for dialysis in patients
with end-stage renal failure[1-3] owing to their advantages
of a lower cost, economical use of available veins, and
reduced risk of infection and steal syndrome.[3-6] On
the other hand, one major drawback of them is their
moderate patency rate of around 62% at one year.[3,6-10]
Most cases of radiocephalic AV fistula failure occur
due to stenosis in close proximity to the anastomotic
site in 55-75% of the patients.[11,12]

In coronary artery bypass surgery, better patency
rates have been reported with saphenous vein graft
harvesting technique sparing the perivascular tissues
compared to that performed without preservation of
the perivascular tissues.[13-17] It has been proposed that
vein preparation with preservation of the perivenous
vascular tissues may reduce the injury at the vein wall
and protect vasa vasorum, in addition to reducing
venospasm and preventing kinking through mechanical
support.[15] Furthermore, perivascular tissue is a source
of relaxing factors derived from adipocytes such as
leptin and adiponectin, which may potentially be
involved in promoting graft patency.[18.19]

Minimizing surgical trauma through sparing of
perivenous vascular tissues during AV fistula surgery
might have similar favorable effects resulting in better
patency rates. However, studies examining the role
of perivascular tissue preservation in improving the
patency of AV fistulas for dialysis are scarce in
number.[20]

Therefore, in this study, we aimed to compare the
patency rates of radiocephalic AV fistulas prepared
through preservation of the perivenous vascular tissues
versus those prepared using the conventional technique.

Methods

A total of 169 patients (107 males, 62 females; mean
age 59.5 years; range, 39 to 87 years) who underwent a
radiocephalic AV fistula construction at Private Erdem
Hospital between January 2011 and August 2015
were included in this study. In 95 patients, the tissues
surrounding the cephalic vein were stripped off as per
the conventional method, while the no-touch technique
preserving the perivenous vascular tissues was utilized
for harvesting in 74 patients. All patients were followedup
to compare primary and secondary patency rates at
one year. The study protocol was approved by the
Private Erdem Hospital Ethics Committee. A written
informed consent was obtained from each patient. The
study was conducted in accordance with the principles
of the Declaration of Helsinki.

Prior to surgery, the vascular dimensions were
all measured with Doppler ultrasound by the same
surgeon, who actually carried out all of the procedures.
Patients with no distal pulses or tri-phasic flow, or
those with severe calcification of the radial artery were
excluded from the study, as those which had a cephalic
vein diameter of less than 2 mm after application of a
tourniquet. Also excluded from the study group were the
patients with a prior snuffbox or antecubital AV fistula.

A single dose of 100 mg acetylsalicylic acid
was given prior to the procedure and the same was
continued after the procedure in patients without any
contraindication. All 169 procedures were performed
under local anesthesia without administration of
systemic heparin. In the conventional group, veins
were stripped off as usual with care not to damage the
veins (Figure 1), while a 2-3 mm fat tissue was spared
around the veins in the "no-touch" group with care not
to touch the vein itself (Figure 2). No cautery was used
in both groups in locations adjacent to the vein, while
further avoidance was practiced at the posterior part
of the cephalic vein close to the nerve. In both groups, veins were gently inflated using warm sterile saline
solution containing heparin. A 4 to 6 mm arteriotomy
was performed on the radial artery depending on the
diameter of the vein. After arteriotomy, the radial
artery was rinsed with a solution containing heparin.
An end-to-site anastomosis was performed using
8/0 prolene sutures under 3.5¥ magnification with
surgical loupes (Figures 3 and 4).

Follow-up visits were scheduled at one week, and
one, three, six, and 12 months after the procedure.
Presence of a thrill postoperatively and uneventful
completion of dialysis sessions following maturation
were both required for the fistula to be considered
functional. Primary patency was defined as a patent
fistula without any need for an additional procedure
at one year. Secondary patency was defined as the
presence of a functional fistula at one year with or
without additional procedures.

Statistical analysis
IBM SPSS version 21.0 (IBM Corp., Armonk,
NY, USA) was used for the analysis of data. Data
were presented in mean ± standard deviation or
number (percentage), where appropriate. Normality
was tested using hypothesis tests and graphical
methods. Intergroup comparisons of continuous data
were carried out using Mann-Whitney U test or
Student-t test for independent samples, depending on
the distribution. Categorical data were compared using
Pearson chi-square test. A p value of less than 0.05 was
required for statistical significance.

All fistulas were functional right after fistula
construction and all patients had a successful initial
session of hemodialysis through the constructed fistula.
AV fistula failure developed in 22 patients within
the first year following the operation resulting in
primary patency rates of 90.5% versus 84.2% for the
no-touch and the conventional group, respectively
(p=0.225). Among these 22 failures, 14 were suitable
for endovascular therapy; however, the remaining
eight patients had complete obstruction precluding an
endovascular intervention through balloon angioplasty.
Of the 14 failures that were amenable to endovascular
therapy, 11 patients (78.6%) had successful interventions.
Of all these patients, only one patient had a balloon
angioplasty for a stenosis at the level of cephalic arch.
All the remaining patients (n=13) had perianastomotic
stenosis, i.e., within 2 cm of the anastomosis site.
The distribution of perianastomotic stenosis was 4/74,
5.4% for the no-touch group versus 9/95, 9.5% for the
conventional group; p=0.39. In an additional one patient
with steal syndrome but with a functioning fistula, distal
radial artery ligation resulted in cessation of symptoms.
Secondary patency rates were 94.6% versus 93.7% for
the no-touch and the conventional group, respectively
(p=0.803). The two groups did not differ regarding
primary or secondary patency rates. In the remaining
10 patients, a new fistula was created (n=5, 50%) or a
catheter was placed (n=5, 50%) for hemodialysis access.
None of the patients received transplantation during the
follow-up period.

Discussion

Considering the favorable results obtained with
the no-touch technique employed for saphenous vein
preparation during coronary artery bypass grafting
operations, this study aimed to assess and possibly
repeat a similar outcome utilizing a similar technique
for vein preparation during creation of radiocephalic
AV fistulas for hemodialysis access. According to our
research in Pubmed and Google Scholar in the English
literature, this study was one of the very few or the first
to compare the patency rates of a no-touch technique
preserving the perivenous vascular tissues with that of
the conventional technique for radiocephalic AV fistula
construction. However, the differences in the primary
and secondary patency rates between these two groups
did not reach a statistical significance.

Evidence supporting the benefits of a no-touch
technique comes from several recent studies regarding
saphenous vein preparation for coronary artery bypass
surgery. In their randomized study, Souza et al.[14] found
better graft patency rates at 18 months with the no-touch
group compared to the conventional group, results of which were persistent at eight-and-a-half years.
In addition, no-touch technique has been associated
with better endothelial integrity when compared to the
conventional technique particularly when the levels
of adenosine, nitric oxide synthase, and vascular
endothelial growth factor immunoreactivities[21]
suggesting slower progression of atherosclerosis are
taken into account.[22] A meta-analysis has supported
these findings.[17]

Better patency rates with saphenous vein grafts
harvested for coronary artery bypass grafting with
no-touch technique have been explained by several
mechanisms. A lesser amount of injury potentially
preventing the occurrence of an early intimal
hyperplasia,[13,14] a lower risk of manipulation, thus
preventing spasm and kinking,[15] better preservation
of feeding vessels to maintain oxygen and nutrients to
the wall,[14,16,23] continuing release of relaxing factors
from adipocytes,[18,19] and decreased inflammation
due to perivenous adipose tissue-related biochemical
factors[22,24-27] were proposed as potential explanations
favoring use of a no-touch technique. However, whether
all these factors apply similarly for saphenous vein
grafts and cephalic vein used in AV fistula creation
remains to be answered since the two vessels differ
both anatomically and physiologically. For example,
cephalic vein grafts have far lesser amounts of fat
tissue compared to the saphenous veins harvested.
In addition, in contrast to saphenous vein grafts, AV
fistulas are in-situ and have higher flows.

To the best of our knowledge, the only other study
that described and sought the functional outcomes
of radiocephalic fistulas created using a non-touch
technique was reported by Hörer et al.[20] This study
reported primary and secondary patency rates of 54%
and 80% at one year, respectively. The study by Hörer
et al.[20] differs from our study both in terms of study
design and preoperative vessel size. They did not have
a control group for comparison but instead reported the
functional outcomes of 31 patients all operated using
the same technique. This study was mainly focused
on vessel size as a potential predictor of patency and
also included patients with small-sized vessels. Most
patients had either a small sized vein or artery (≤2 mm)
and more than one-third had small-sized cephalic vein
(≤2 mm) with a mean distal cephalic vein diameter of
2.4 mm. In our study, on the other hand, those who
had a cephalic vein diameter of less than 2 mm were
excluded. The lower patency rates in Hörer's study
compared to ours may be explained by this difference
in cephalic vein size. Nevertheless, considering the
anatomic characteristics of those patients, trying radiocephalic fistula at wrist level before other options
seems to be justified, particularly with the 80%
secondary patency rate at one year. They also mention
that their no-touch technique allows for the possibility
of creating fistula at distal level in patients who are
not usually considered eligible for a distal forearm
fistula. However, it is of note to emphasize that patency
rates were similar in that study across the two groups
based on cephalic vein size (>2 mm versus ≤2 mm),
which may be well explained by the small sample size
precluding adequate statistical power.

To begin with, surgery with a no-touch technique
may last slightly longer than the conventional technique.
Medial and lateral branches of the superficial radial
nerves course just beneath cephalic vein at wrist level,
making them susceptible to trauma. Using cautery
during cephalic vein preparation may be unpleasant for
the patient. Therefore, making dissection at this region
with scissors and separating the nerve using an elastic
tape would provide comfort for both the patient and the
surgeon (Figure 2).

Graft failures after fistula surgery and coronary
artery bypass surgery have several differences. Most
fistula failures, particularly for radiocephalic fistulas,
are due to intimal hyperplasia at perianastomotic site,
as it was the case in our study. No-touch technique
aimed to address this problem and protect the
perianastomotic site in particular. Peri-graft adipose
tissue has the potential to minimize trauma and protect
the vasa vasorum, thereby preventing vascular injury
and kinking. However, several other factors including
flow dynamic changes at needle insertion sites may
well be responsible for fistula loss.

The main limitation of our study may be the
small sample size, which might have prevented the
achievement of a statistically significant difference,
although patency rates were higher numerically with
the no-touch group. Nevertheless, patency rates were
quite high and satisfactory in both groups which may
be attributed to the following factors: (i) all patients
were operated by a single surgeon experienced in
fistula creation and fine vascular anastomoses, (ii) all
patients had venous diameter greater than 2 mm based
on inclusion criteria, and (iii) e xtreme c aution w as
exercised in both groups for not traumatizing the
vessels and to avoid kinking. Another limitation
of the study is the absence of any pathological or
histochemical examination of the vessels, which
might have shed light on the possible mechanisms
related to the potential benefits of the no-touch
method.

In conclusion, the no-touch technique seems to
represent a viable option for patients undergoing
radiocephalic arteriovenous fistula construction.
However, it is not clear whether the same benefits exist
for this limited length of conduit; and findings of this
study do not support the superiority of the no-touch
technique in terms of functional outcomes compared
to the conventional technique.

Declaration of conflicting interests
The authors declared no conflicts of interest with respect to
the authorship and/or publication of this article.

Funding
The authors received no financial support for the research
and/or authorship of this article.

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